MONDAY, Aug. 5 (HealthDay News) -- For women who are trying to get pregnant, there is no evidence that taking antioxidant supplements will improve their chances, a new review shows.

Researchers analyzed data from 28 clinical trials that included a total of 3,548 women attending fertility clinics. Women who took antioxidant supplements were no more likely to become pregnant than those who took an inactive placebo or received standard treatment, including folic acid.

The findings were published Aug. 5 in The Cochrane Library.

"There is no evidence in this review that suggests taking an antioxidant is beneficial for women who are trying to conceive," lead researcher Marian Showell, who works in obstetrics and gynecology at the University of Auckland, in New Zealand, said in a journal news release.

Showell's team also found only limited information about potential dangers associated with taking antioxidant supplements, such as miscarriage and ectopic pregnancy. Only 14 of the 28 trials looked at harmful effects. They found that the risk was no higher in women taking antioxidants than in those who received a placebo or standard treatment.

Overall, the quality of the clinical trials was low or very low and the number of different antioxidants tested in the trials made it difficult to make comparisons, according to the researchers.

"We could not assess whether one antioxidant was better than another," Showell said.

About one-quarter of couples who want to have a baby have difficulty conceiving, the authors noted in the news release. Women undergoing fertility treatment often take dietary supplements, including antioxidants, to try to boost their odds of becoming pregnant. But many antioxidant supplements are unregulated and there is limited evidence on their safety and effects, the researchers concluded.